Safety evaluation of amylomaltase from Thermus aquaticus.

A recombinant amylomaltase, MQ-01, obtained by cultivation of Bacillus subtilis expressing the amylomaltase gene from Thermus aquaticus is to be used in the production of enzymatically-synthesized glycogen; which is intended for use as a food ingredient. In order to establish the safety of MQ-01, the enzyme was subjected to standard toxicological testing. In a battery of standard Salmonella typhimurium strains (TA98, TA100, TA1535, and TA1537) and in Escherichia coli WP2 uvrA, both with and without metabolic activation, MQ-01 failed to exhibit mutagenic activity. Similarly, MQ-01 did not display clastogenic properties in Chinese hamster lung fibroblast cells (CHL/IU), in an in vitro chromosomal aberration assay. In a 13-week subchronic toxicity study in rats, oral administration of MQ-01 at doses of up to 15 mL/kg body weight/day (corresponding to approximately 1230 mg/kg body weight/day) did not produce compound-related clinical signs or toxicity, changes in body weight gain, food consumption, hematology, clinical chemistry, urinalysis, organ weights, or in any gross and microscopic findings. The results of this study support the safety of MQ-01 in food production.